In the related art, there has heretofore been known a hybrid vehicular power transmitting apparatus including a first shifting portion and a second shifting portion. The first shifting portion acts as a differential portion connected to a prime mover, such as an internal combustion engine or the like, to be operative to perform a differential action. The second shifting portion acts as an automatic shifting portion forming part of a power transmitting path extending from the first shifting portion to drive wheels. For instance, Patent Gazette 1 (Japanese Patent Application Publication No. 2006-46487) discloses such a hybrid vehicular power transmitting apparatus. With a control device for such a hybrid vehicle power transmitting apparatus, a normal-operation disabling state may be caused in some cases, i.e., a failure occurs in either one of the first and second shifting portions. Then, a speed ratio of the other shifting portion, available to perform a normal operation, is altered so as to suppress the occurrence of fluctuation in speed ratio of an entire power transmitting apparatus mentioned above. In such a case, alternatively, the other shifting portion, available to perform the normal operation, is placed in a neutral state causing the power transmitting path to be disconnected.
With the control device for the hybrid vehicular power transmitting apparatus disclosed in Patent Gazette 1, executing such a control operation is deemed to provide an effect of minimizing an adverse affect on the vehicle running caused by the occurrence of the failure in the first and second shifting portions. However, if such a failure or the like occurs, then the prime mover may be caused to suddenly stop during the running of the vehicle propelled by the prime mover as the drive-force source. If the prime mover suddenly stops in such a way, a rotary element of the first shifting portion is caused to reach a high-speed rotation due to the occurrences of the sudden stop of the prime mover and the differential action of the first shifting portion acting as the differential portion. Thus, it is considered a drop i.e. decrease may occur in durability of the first shifting portion and related component parts or the like. In addition, no solution is disclosed in Patent Gazette 1 for addressing such an issue arising when the prime mover is caused to suddenly stop.